code: def file_claims_pdfa(filename: Path):
      """Determines if the file claims to be PDF/A compliant.
  
      This only checks if the XMP metadata contains a PDF/A marker. It does not
      do full PDF/A validation.
      """
      with pikepdf.open(filename) as pdf:
          pdfmeta = pdf.open_metadata()
          if not pdfmeta.pdfa_status:
              return {
                  "pass": False,
                  "output": "pdf",
                  "conformance": "No PDF/A metadata in XMP",
              }
          valid_part_conforms = {
              "1A",
              "1B",
              "2A",
              "2B",
              "2U",
              "3A",
              "3B",
              "3U",
          }
          conformance = f"PDF/A-{pdfmeta.pdfa_status}"
          pdfa_dict: dict[str, str | bool] = {}
          if pdfmeta.pdfa_status in valid_part_conforms:
              pdfa_dict["pass"] = True
              pdfa_dict["output"] = "pdfa"
          pdfa_dict["conformance"] = conformance
      return pdfa_dict
  
file_path: OCRmyPDF/src/ocrmypdf/pdfa.py
imports: from __future__ import annotations
  import base64
  from collections.abc import Iterator
  from importlib.resources import files
  from pathlib import Path
  import pikepdf
label_desc: Use image node_id 4 for calling a global function with example usage: file_claims_pdfa(filename) and returns: pdfa_dict, dict